Transform Domain Watermarking of Image Signals

1. A method of embedding a watermark in an image comprising: receiving transform coefficients of the image; changing the value of selected coefficients to embed multi-bit message data in the coefficients, the changing including controlling the changing of the coefficients such that the changing embeds the data and forms an orientation signal that facilitates determination of rotation or scale of the image.

2. The method of claim 1 wherein the transform coefficients comprise Discrete Cosine Transform coefficients.

3. The method of claim 1 wherein the transform coefficients are extracted from compressed image blocks.

4. The method of claim 1 wherein the data comprises message bits, and a message bit is mapped to selected transform coefficients.

5. The method of claim 4 wherein the change of the selected transform coefficients to embed the watermark is modified by a characteristic of the image.

6. The method of claim 4 wherein the change of the selected transform coefficients to embed the watermark is modified to control bit rate of the image according to a bit rate limit.

7. The method of claim 1 wherein the orientation signal is formed by embedding message bits according to an embedding rule.

8. The method of claim 1 wherein the transform coefficients form part of a video.

9. A method of embedding a watermark in an image comprising: receiving message bits to be embedded in the image; receiving transform coefficients of the image; mapping the message bits to selected transform coefficients; changing the value of selected coefficients to embed data in the coefficients; wherein characteristics of the image are used to control the change of transform coefficients to embed the watermark, and a bit rate control is used to modify the change of transform coefficients to embed the watermark according to a bit rate limit.

10. The method of claim 9 wherein each of the message bits are mapped to selected transform coefficients.

11. The method of claim 10 wherein the image comprises at least part of an MPEG video.

12. A computer readable medium on which is stored instructions for performing a method of embedding a watermark in an image, the method comprising: receiving transform coefficients of the image; changing the value of selected coefficients to embed multi-bit message data in the coefficients, the changing including controlling the changing of the coefficients such that the changing embeds the data and forms an orientation signal that facilitates determination of rotation or scale of the image.

13. The computer readable medium of claim 12 wherein the transform coefficients form part of a video.

14. A computer readable medium on which is stored instructions for performing a method of embedding a watermark in an image, the method comprising: receiving message bits to be embedded in the image; receiving transform coefficients of the image; mapping the message bits to selected transform coefficients; changing the value of selected coefficients to embed data in the coefficients; wherein characteristics of the image are used to control the change of transform coefficients to embed the watermark, and a bit rate control is used to modify the change of transform coefficients to embed the watermark according to a bit rate limit.

15. The computer readable medium of claim 14 wherein the transform coefficients form part of a video.